customers cannot checkout error 10002

I am suddenly having problems with my checkout. PayPal processes all credit card payments on my web site. It seems to be a problem with my API. I've tried copying and pasting the username, password and security signature from paypal to my payments module in my admin several times, but it doesn't help.

When I try test checkouts I get emails with this message:

ALERT: PayPal Express Checkout Error (10002)
10002 Security error - Security header is not valid

No one at Paypal has been able to help me. They said that it may be a problem with zen cart. That maybe I need to get an updated api signature.

Any help?

Thanks

if you go to modules->Payment->Paypal is your API username/password/correct?
Are you using the correct Paypal module for your paypal account?
Are you using an SSL? is it a Shared SSL?

Try the advice in post #11 here:

https://www.zen-cart.com/showthread.php?61669-Paypal-error-10002-misconfigured-mixed-live-and-sandbox

Thanks, I tried that, but it didn't help. Someone at PayPal suggested that maybe there had been a zen cart update that changed the security signature, and that I may be able to get the new security signature on a zen cart forum.

I had the same error message by e-mail. I talked to PayPal. he said it was usually associated with a sand box error. The email I got is not from Pay Pal . I know this because I have a different e-mail associated with PayPal. The email I got that said PayPal Express Checkout Error (10002) came from my Zen cart email to my zen cart email. I did this fix.... http://www.zen-cart.com/showthread.p...ghlight=poodle everything seem to be working. So I believe this error message is from playing with the sandbox before doing the above fix.